KR20070030669A - Preparation of polyvinyl chloride-based copolymer resin for plastisol - Google Patents

Abstract

The present invention relates to a method for producing a vinyl chloride copolymer resin for plastisol processing, by the suspension co-polymerization by adding a comonomer and a buffer having a low glass transition temperature at the beginning of the reaction, excellent low-temperature meltability and a constant particle size A vinyl chloride-based copolymer resin having a narrow distribution can be prepared, and by adding the copolymer resin to the plastisol as a blend resin, the viscosity of the plastisol can be lowered to facilitate processing even at a lower temperature.

Plastisols, vinyl chloride resins, dispersants, buffers, comonomers

Description

Method for producing vinyl chloride copolymer resin for plastisol processing {Preparation of polyvinyl chloride-based copolymer resin for plastisol}

1A to 1D are electron micrographs of a vinyl chloride resin or a vinyl chloride copolymer resin obtained in Examples and Comparative Examples.

The present invention provides a method for producing a vinyl chloride copolymer resin for plastisol processing that can provide a vinyl chloride-based plastisol having a low particle size, a uniform particle size distribution, and excellent low temperature meltability and excellent processability at low temperatures. It is about.

Vinyl chloride resin is the most widely used general purpose resin in the world for living and industrial use. Straight vinyl chloride resin is manufactured by suspension polymerization method with powder particles of 100 ~ 200 ㎛ size, and paste vinyl chloride resin is 0.1 ~ 2. It is prepared by emulsion polymerization method with powder particles having a size of about μm. The paste vinyl chloride resin is usually dried by a spray drying method of latex obtained by emulsion polymerization to form final resin product particles of 5 탆 or more. The paste resins thus prepared are dispersed in solvents or plasticizers to reverse roll-coating, knife coating, screen coating, spray coating, gravure and screen printing, rotation casting, shell casting, It is applied to products such as flooring, wallpaper, tarpaulin, raincoats, gloves, automotive underbody coating and carpet tiles through processes such as shell casting and dipping.

Paste vinyl chloride resin is usually processed and molded into a plastisol state composed of various additives such as a heat stabilizer together with a plasticizer, and in order to facilitate processing, it is important to maintain the flowability of the sol by lowering the viscosity.

In order to achieve this purpose, a suspension polymerized vinyl chloride resin having a size of 30 to 40 μm is conventionally mixed with 10 to 20% of a paste vinyl chloride resin plastisol to lower the viscosity of the sol and improve flowability, thereby providing excellent processability. Method has been used. Suspension polymerized vinyl chloride resin having a particle size of 30 to 40 µm used for this purpose is commonly referred to as filler PVC, also known as blend resin or extender resin. The vinyl chloride resin is a homopolymer or copolymer of vinyl chloride monomer. Filler PVC (extender resin, blend resin) should have low absorption of plasticizer or solvent and have uniform particle size distribution in order to show good flow behavior in high and low shear during sol processing, ie to reduce sol viscosity. The important property of filler PVC is that the proper particle size and uniform distribution of particle size are important because paste sol is used to paint or film such as floor coating, can coating, wallpaper production process, automotive underbody spray coating, etc. This is because the coating film thickness of the process for preparing the thin film is about 50 μm or less, and the particle size in the range of 30 to 40 μm is ideal for forming a uniform coating layer or film. When the content of the particles smaller than the above range is high, the viscosity lowering effect is attenuated and the processability of the plastisol is reduced. When the content of the particles larger than the above range is high, the uniformity and stability of the coating layer and the film are lowered and the quality of the final molded product is reduced. It will cause a loss.

Such vinyl chloride polymer resins or vinyl chloride copolymer resins for plastisol processing are generally prepared by suspension polymerization or suspension copolymerization using polyvinylalcohol (PVA), cellulose, and gelatin-based dispersants. However, when using a dispersant, the particle size and particle size distribution of the resulting polymer or copolymer may vary depending on the stability of the protective colloid.

On the other hand, when manufacturing a sol or carpet tile for automotive underbody coating for the purpose of dustproof, anticorrosion and abrasion prevention using paste resin, in order to realize the reduction of energy cost, the composition of the resin is conventionally changed by using a low temperature hardener. By improving the low temperature workability and wear resistance, but this has a problem of weak durability and fragile impact.

The present inventors have studied to solve the above problems, and as a result, by adjusting the pH to an appropriate range at the beginning of the polymerization reaction, the stability of the protective colloid formed by the dispersant is increased, and the low temperature meltability is achieved by using a comonomer having a low glass transition temperature. The present invention was completed by knowing that an excellent vinyl chloride copolymer resin can be prepared.

Therefore, the first technical problem to be achieved by the present invention is to have a low temperature meltability that can be used as a blend resin to obtain a vinyl chloride-based plastisol composition having excellent processability at low temperature, and has a particle size of 30 to 40 μm and a narrow particle size. It is to provide a method for effectively producing a vinyl chloride copolymer resin having a distribution.

The second technical problem to be achieved by the present invention is to provide a vinyl chloride-based plastisol composition having excellent processability and low viscosity at low temperature.

In order to achieve the above technical problem, in the first aspect of the present invention, a vinyl chloride monomer and a vinyl acetate or (meth) acrylate-based comonomer are buffered at a pH of 4 to 10 at the beginning of the copolymerization reaction during suspension copolymerization in the presence of a dispersant and a reaction initiator. A method of preparing a vinyl chloride copolymer for plastisol processing is provided by adding a buffer having a region.

According to one embodiment of the invention the buffer is NaHCO ₃ , Na ₂ B ₄ O ₇ , KH ₃ C ₄ O ₈ , KHC ₄ H ₄ O ₆ , KHC ₈ H ₄ O ₄ , Ca (OH) ₂ , KH ₂ It may be at least one selected from the group consisting of PO ₄ , Na ₂ CO ₃ , Na ₂ HPO ₄ and NH ₄ OH.

According to another embodiment of the present invention, the comonomer may be added in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the vinyl chloride monomer.

According to another embodiment of the present invention, the buffer may be added in an amount of 0.001 to 0.04 parts by weight based on 100 parts by weight of the vinyl chloride monomer.

In a second aspect of the present invention, a paste vinyl chloride resin; Plasticizers; And it provides a vinyl chloride-based plastisol composition comprising a vinyl chloride copolymer having a particle size of 30 ~ 40 ㎛ prepared by the above method.

The vinyl chloride copolymer prepared by the method according to the present invention has a particle size of 30-40 μm, has a uniform particle size distribution, has excellent low temperature meltability, and when used as a blend resin, it is excellent in processability at low temperatures and has a low viscosity. A stisol composition can be obtained.

Hereinafter, the present invention will be described in more detail.

The present invention can be processed at a lower temperature than the conventional processing temperature to apply to products that require low-temperature melting and dust-proof, rust-proof, abrasion resistance, vinyl chloride-based vinyl chloride-based plastisol for energy saving effect The present invention relates to a method for preparing a copolymer resin, wherein the vinyl chloride monomer and vinyl acetate or (meth) acrylate-based comonomer are suspended and co-polymerized in the presence of a dispersant and a reaction initiator, so that a buffer region at the initial stage of the copolymerization reaction when the vinyl chloride copolymer is prepared is pH. It is characterized by the addition of 4 to 10 buffer.

In the present invention, the vinyl chloride copolymer resin means a resin having a vinyl chloride content of 50 wt% or more and 97 wt% or less in the final resin composition.

In the present invention, in order to make the vinyl chloride-based copolymer resin for plastisol processing have low temperature melting property, vinyl acetate or (meth) acrylate-based comonomer is added to the vinyl chloride monomer to suspend copolymerization. The glass transition temperature of the comonomer is typically -50 ° C to 40 ° C.

Examples of the (meth) acrylate-based copolymers include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl (meth) acrylate, sec-butyl acrylate, isobutyl acrylate and cumyl Acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-methylheptyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, myristyl (meth) acrylate, n-nonyl (meth) acrylate, palmityl methacrylate, stearyl It may be at least one selected from the group consisting of methacrylate, 2-hydroxy ethyl acrylate, 2-hydroxy propyl acrylate, and mixtures thereof.

The vinyl acetate or (meth) acrylate-based comonomer may be used in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the vinyl chloride monomer. When the vinyl acetate or (meth) acrylate comonomer is less than 0.1 parts by weight, it may be difficult to express low temperature processing properties, and when the vinyl acetate or (meth) acrylate comonomer is more than 20 parts by weight, the cost of the comonomer may be increased and the content of the comonomer that is relatively lost may be increased.

In the present invention, in order to make the vinyl chloride-based copolymer resin for plastisol processing have a small particle size and a uniform particle size distribution, a buffer added at the beginning of the suspension copolymerization reaction has a buffer region of pH 4 to 10, NaHCO ₃ , Na ₂ B ₄ O ₇ , Na ₂ HPO ₄ , Na ₂ CO ₃ , KH ₂ PO ₄ , KH ₃ C ₄ O ₈ , NH ₄ OH, KHC ₄ H ₄ O ₆ , KHC ₈ H ₄ O ₄ And Ca (OH) ₂ can be used.

The buffer may be used in an amount of 0.001 to 0.04 parts by weight based on 100 parts by weight of the vinyl chloride monomer. When the buffer amount is less than 0.001 parts by weight, it is difficult to stabilize the colloid because it is difficult to control the pH at the beginning of the reaction, and therefore, it is difficult to have a proper particle size and uniform particle size distribution. This is not good because it is not good.

The dispersant added in preparing the vinyl chloride copolymer according to the present invention is added to improve the suspension stability and to efficiently perform the polymerization reaction. Dispersants usable in the present invention include partially saponified vinyl acetate polymers, cellulose hydroxide, gelatin, acrylate or acrylate copolymers or copolymer resins of polyethylene glycol, polyvinylpyrrolidone or maleic anhydride and styrene. It can be used individually or in combination of 2 or more types. More preferred dispersant in the present invention is a partially saponified vinyl acetate polymer having a saponification degree of 70 to 90 mol% and a 4 wt% aqueous solution viscosity of 30 to 60 cps, or a cellulose hydroxide or gelatin having a viscosity of 1000 cps of a 2 wt% aqueous solution. Preferably, the amount is preferably 0.1 to 0.8 parts by weight based on 100 parts by weight of the vinyl chloride monomer introduced into the reactor in the suspension copolymerization step. If the amount of the dispersant is less than the above range, the stability of the resin particles in the reactor is lowered, so that larger particles of 100 μm or more are formed, making it difficult to use as a resin for processing plastisols. It is formed to cause a problem that the viscosity lowering effect is lowered when using the final resin product.

As a polymerization initiator that can be used in the suspension copolymerization step in preparing the vinyl chloride copolymer according to the present invention, water-soluble initiators such as potassium persulfate, ammonium persulfate and hydrogen peroxide or benzoyl peroxide, lauryl peroxide, acetyl cyclohexanol Peroxide, 2,4,4-trimethylpentyl-2-peroxy neo decanoate, α-cumyl peroxy neo decanoate, dibutyl peroxy dicarbonate, cumene hydroperoxide, t-butyl hydroxy peroxide Organic peroxides such as, and the like, azo initiators such as azobisisobutyronitrile, azobis-2,4-dimethyl valeronitrile and the like can be used.

In more detail, the suspension copolymerization reaction process according to the present invention will be described in more detail, by applying a vacuum to the reactor to remove oxygen in the reactor, and then adding the polymerization water, the buffer, the comonomer, the initiator, and the dispersant in a batch, and then dividing the vinyl chloride monomer in a batch, or After continuous addition and temperature retention at a predetermined reaction temperature, the unreacted residual vinyl chloride monomer was recovered, and the resin in the reactor was separated and dehydrated and hot-air dried to prepare a vinyl chloride copolymer resin having excellent low temperature melting property. do.

The vinyl chloride copolymer resin prepared by the method according to the present invention is mixed with a plastisol comprising a vinyl chloride resin and a plasticizer to obtain a plastisol composition.

The vinyl chloride copolymer resin is preferably included in the plastisol composition in an amount of 10 to 30 parts by weight based on 100 parts by weight of the vinyl chloride resin. When the amount is less than 10 parts by weight, low temperature processability is difficult to be expressed, and when the amount is more than 30 parts by weight, the intrinsic properties of the desired plastisol may be degraded due to the excessive vinyl chloride copolymer resin.

The plastisol composition according to the present invention is excellent in processability at low temperatures and low in viscosity to facilitate molding into a product.

The present invention will be described in more detail with reference to the following examples. The following examples are intended to illustrate the present invention more specifically, but the scope of the present invention is not limited to the following examples.

Example

Example 1

0.6 parts by weight of cellulose dispersant, 5.0 parts by weight of comonomer, vinyl acetate, 250 parts by weight of deionized water in a 1000-liter high-pressure reactor, bis (2-ethylhexyl) peroxydicarbonate (Bis (2-ethylhexyl)) as a reaction initiator peroxydicarbonate) 0.02 parts by weight, t-butyl peroxy pivalate (0.26 parts by weight) and NaHCO ₃ 0.015 parts by weight were added in a batch, vacuum was added and 50 parts by weight of vinyl chloride monomer was added with stirring to 60 ° C. The reaction was terminated when the reactor pressure reached 3.5 kgf / cm ² after the addition of 50 parts by weight of vinyl chloride monomer was carried out by heating the polymerization reaction by increasing the temperature. After the reaction was completed, the unreacted vinyl chloride monomer was recovered and removed, and the reactor was cooled, dehydrated and dried to obtain a vinyl chloride copolymer resin for plastisol processing.

Example 2

0.6 parts by weight of cellulose-based dispersant, 10.0 parts by weight of vinyl acetate as a comonomer, bis (2-ethylhexyl) peroxydicarbonate (Bis (2-ethylhexyl)) as a initiator peroxydicarbonate) 0.02 parts by weight, t-butyl peroxy pivalate (0.26 parts by weight) and NaHCO ₃ 0.015 parts by weight were added in a batch, vacuum was added and 50 parts by weight of vinyl chloride monomer was added with stirring to 60 ° C. The reaction was terminated when the reactor pressure reached 3.5 kgf / cm ² after the addition of 50 parts by weight of vinyl chloride monomer was carried out by heating the polymerization reaction by increasing the temperature. After the reaction was completed, the unreacted vinyl chloride monomer was recovered and removed, and the reactor was cooled, dehydrated and dried to obtain a vinyl chloride copolymer resin for plastisol processing.

Example 3

In a 1000-liter high-pressure reactor, 250 parts by weight of deionized water, 0.6 parts by weight of cellulose dispersant, 10.0 parts by weight of butyl acrylate as a comonomer, bis (2-ethylhexyl) peroxydicarbonate (Bis (2-ethylhexyl) as a reaction initiator ) peroxydicarbonate) 0.02 parts by weight, t-butyl peroxy pivalate (0.26 parts by weight), NaHCO ₃ 0.015 parts by weight of a batch after adding a vacuum and 50 parts by weight of vinyl chloride monomer with stirring and 60 ℃ The reaction was terminated when the reactor pressure reached 3.5 kgf / cm ² after the addition of 50 parts by weight of vinyl chloride monomer was performed after the polymerization reaction was performed by heating up. After the reaction was completed, the unreacted vinyl chloride monomer was recovered and removed, and the reactor was cooled, dehydrated and dried to obtain a vinyl chloride copolymer resin for plastisol processing.

Comparative Example 1

0.6 parts by weight of cellulose dispersant, 250 parts by weight of deionized water, 0.02 parts by weight of bis (2-ethylhexyl) peroxydicarbonate as a reaction initiator in a 1000 liter high pressure reactor, t-butyl 0.26 parts by weight of peroxy pivalate (t-Butyl peroxy pivalate) was added all at once, and vacuum was added, 50 parts by weight of vinyl chloride monomer was added with stirring, and the polymerization was carried out by heating to 60 ° C. The reaction was terminated when the reactor pressure reached 3.5 kgf / cm ² after the addition. After the reaction was completed, the unreacted vinyl chloride monomer was recovered and removed, and the reactor was cooled, dehydrated, and dried to prepare a vinyl chloride resin for processing plastisol.

The average particle diameter and particle size distribution of the vinyl chloride copolymer resin or the vinyl chloride resin obtained in Examples and Comparative Examples are shown in Table 1 below.

Example 1 Example 2 Example 3 Comparative Example 1 Average particle size (㎛) 33 34 35 34 Particle size distribution 1.10 1.09 1.08 1.62 Content of Particles with Particle Size of 149㎛ or More (%) 0.0 0.0 0.1 5.4

From Table 1, it can be seen that as the buffer is added at the beginning of the polymerization reaction, a vinyl chloride copolymer having a uniform particle size distribution, no large particles, and an average particle diameter of 30 or 40 μm is obtained.

In addition, the melting temperature of the vinyl chloride copolymers obtained in Examples and Comparative Examples was measured using a RMS (Rheometrics Mechanical Spectrometer) and the results are shown in Table 2 below.

Example 1 Example 2 Example 3 Comparative Example 1 Melting temperature (℃) 178.1 178.0 178.3 182.4

As can be seen in Table 2, it can be seen that the vinyl chloride copolymer resin prepared according to the present invention has excellent low temperature melting property.

An electron micrograph of the vinyl chloride copolymer or the vinyl chloride resin obtained in Examples and Comparative Examples is shown in FIG. 1. Figure 1a is Example 1, Figure 1b is Example 2, Figure 1c is Example 3, Figure 1d is an electron micrograph of the vinyl chloride resin obtained in Comparative Example 1. As shown in Figure 1 it can be seen that the vinyl chloride copolymer resin obtained in the example has a uniform particle size distribution compared to the vinyl chloride resin obtained in the comparative example.

10 to 20 parts by weight of the vinyl chloride-based copolymer or vinyl chloride resin obtained in Examples and Comparative Examples and 120 to 150 parts by weight of a plasticizer, based on 100 parts by weight of the paste vinyl chloride resin (manufacturer name: LG product name: paste vinyl chloride resin) Addition was then solved through the mixing process and aged at 25 ° C. and Brookfield viscosity was measured and the results are shown in Table 3 below.

Example 1 Example 2 Example 3 Comparative Example 1 Plastisol viscosity (cps) 2,100 2,050 2,210 2,800

As can be seen in Table 3, it can be seen that the viscosity is lowered when the vinyl chloride copolymer prepared by the method according to the present invention is added to the plastisol as a blend resin. In addition, it is possible to obtain a plastisol having excellent processability at a low temperature.

As described above, the present invention imparts low-temperature meltability by initially adding, dividing or continuously adding the comonomer and vinyl chloride monomer having a low glass transition temperature during suspension copolymerization, and adding a buffer at the beginning of the polymerization reaction. By adjusting the initial pH to maintain the protective colloidal stability of the dispersant, it is possible to prepare a vinyl chloride-based copolymer resin for processing plastisol excellent in low-temperature meltability having an appropriate particle size and narrow particle size distribution, which is used as a blend resin It can be added to sol and applied to products requiring dust, rust and antiwear properties.

Claims (6)

To prepare a vinyl chloride copolymer by adding a buffer having a buffer region of pH 4 to 10 at the beginning of the copolymerization reaction during suspension copolymerization of a vinyl chloride monomer and a vinyl acetate or (meth) acrylate-based comonomer in the presence of an initiator and a dispersant. Way. The method of claim 1, wherein the buffer is NaHCO ₃ , Na ₂ B ₄ O ₇ , KH ₃ C ₄ O ₈ , KHC ₄ H ₄ O ₆ , KHC ₈ H ₄ O ₄ , Ca (OH) ₂ , KH ₂ PO ₄ , Na ₂ CO ₃ , Na ₂ HPO ₄ And NH ₄ OH characterized in that at least one member selected from the group consisting of. The method of claim 1, wherein the vinyl acetate or (meth) acrylate-based comonomer is added in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the vinyl chloride monomer. The method of claim 1, wherein the buffer is added in an amount of 0.001 to 0.04 parts by weight based on 100 parts by weight of the vinyl chloride monomer. Paste vinyl chloride resin; Plasticizers; And vinyl chloride plastisol composition comprising a vinyl chloride copolymer having a particle size of 30 to 40 ㎛ prepared by the method according to any one of claims 1 to 4. The plastisol composition according to claim 5, wherein the vinyl chloride copolymer is contained in an amount of 10 to 30 parts by weight based on 100 parts by weight of the paste vinyl chloride resin.

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